1. Field of the Invention
This invention relates to a microscope, and more particularly to a microscope, wherein selection of magnification, focusing and the like are automatically performed.
2. Description of the Prior Art
The well-known microscopes have heretofore required fine adjusting operation and skills for observing objects to be observed in sharp image formation. For this reason, it has been difficult to observe the objects rapidly and in large quantities during the industrial production processes, and necessity has been voiced for a microscope, wherein the process from the selection of magnification to the focusing is automatically performed.
Here, when the adjusting operation of the microscope is to be automated, particularly, the focusing is to be automated, such a problem is presented that, unless the automatic focusing mechanism is rendered compact in size and light in weight, it is not the microscope.
For example, when a DC servo mechanism is adopted for a mount where the object to be observed is rested, the servo mechanism is large-sized and needs a braking device to hold a static position, so that the requirements for compactness and light weight cannot be satisfied.
Furthermore, when such a construction is adopted that the mount is driven by a stepping motor, in order to effect highly accurate positioning, the stepping motor should be connected to a driving shaft of the mount through a reduction gear. Then, such disadvantages are presented that backlash occurs as the microscope is increased in its size and heat during the operation is notably raised to secure a retarding torque.
Furthermore, the reduction ratio of the reduction gear should be set at 1/70 or more, and it is difficult to obtain the reduction ratio of this kind.
Additonally, it is possible to complete the automatic focusing adjustment of an objective for a few seconds by use of the conventional well-known means. However, it takes much time for rotation of a revolver selection the objective as the pre-operation, and, in addition to it, if a confirmation work for collating the relationship between the objective and the magnification is performed, then the additional working time period of 30 sec or more is needed.
For this reason, the validity of the automatic focusing device is diminished.
Moreover, when the automatic focusing adjustment of the objective is performed, the moving time and accuracy of the mount to the focusing position of the objective raise problems.
More specifically, in order to lesson the time for setting the microscope, it is desirable to move the mount at high speed. However, when the mount is moved at high speed, it is difficult to bring the mount into a static state at the optimal position, whereby hunting and the like tend to occur and, in general, with the microscope, the moving stroke of the mount is relatively small, thus presenting an additional problem.
On the other hand, when the mount is moved at slow speed, it becomes difficult to set the microscope quickly.
Furthermore, in performing the automatic focus adjustment of the objective, the lightness of the object to be observed should be at a predetermined level or more, and this lightness differs depending on the magnification of the objectives, and, unless the lightness of the object to be observed can be automatically adjusted, the validity of the automatic focus adjusting mechanism is diminished.